Serum antibody
enzyme-linked
immunosorbent assay is the most commonly used test for diagnosis of Mycobacterium avium subsp.
paratuberculosis infection in ruminants. However, the assay requires serum preabsorption with Mycobacterium phlei
proteins to reduce cross reactions potentially contributed by the exposure of livestock to environmental mycobacteria. To trial the discovery of novel
antigens which do not require serum absorption, synthetic MAP-specific
peptides were selected based on in silico research to identify putative
B cell epitopes. Four
peptides from previously identified stress-regulated
proteins were synthesized and evaluated using
enzyme linked
immunosorbent assay to detect Mycobacterium avium subsp.
paratuberculosis specific
antibodies in sheep. Two
peptides were from hypothetical MAP
proteins (MAP3567 and MAP1168c) and two were from
proteins with known function (MAP2698c, an
acyl-acyl carrier protein desaturase-DesA2 and MAP2487c a
carbonic anhydrase). The ability of each
peptide to discriminate between unexposed and MAP exposed (infected and vaccinated) animals was similar to that of the parent recombinant MAP
antigen, with area under receiver operating curve values of 0.86-0.93. Assays run with a combination of two
peptides showed slightly higher reactivity than those of individual
peptides.
Peptides evaluated in this study had diagnostic potential similar to corresponding
recombinant proteins but not superior to a complex native MAP
antigen or a commercial assay. Further study is required to investigate other
peptides for their diagnostic potential, and this may be simpler and cheaper than
subunit protein-based research.